1. Field of the Invention
The present general inventive concept relates to a lens, a method of fabricating the lens, and a light scanning unit including the lens, and more particularly, to a lens with low birefringence, a method of fabricating the lens, and a light scanning unit including the lens.
2. Description of the Related Art
Light scanning units are used to scan a predetermined region with light emitted from a light source. Light scanning units are used in various fields. For example, light scanning units are used in scanning type displays and electrophotographic image forming apparatuses such as printers, digital copy machines, and fax machines. In an image forming apparatus, a light beam is emitted from a light scanning unit to a photoconductor such as a photoconductive drum in a main scanning direction by an operation of the light scanning unit and in a sub scanning direction by a movement of the photoconductor, so as to form an electrostatic latent image on the photoconductor. The electrostatic latent image is developed by a developer such as toner, and the developed image is transferred to a printing medium.
The light scanning unit includes a deflector to deflect a light beam emitted from a light source to the photoconductor, and optical devices (lenses) to refract and image the light beam emitted from the light source. Examples of the optical devices are a collimator lens configured to collimate a light beam emitted from a light source, a cylindrical lens configured to condense a light beam onto a reflection surface of a deflector, a synchronization detection lens used to check synchronization of a light beam, and a scanning lens configured to image a light beam deflected from a deflector onto a photoconductor.
Such optical devices of the light scanning unit are usually fabricated through an injection molding process. In this case, however, birefringence is observed in the optical devices due to flow and shrinkage of a resin during the injection molding process. Such birefringence increases aberrations of lenses and increases spot sizes of the lenses, thereby lowering image quality.